To Prove It
by Val-Creative
Summary: Merlin's hands shove off the robe at Arthur's chest, revealing far more scarred, golden skin and a triangular dusting of blond hair. A thumb runs softly over Arthur's collarbone, tracing and circling its shape before Merlin lets it drift, along with his forefinger and middle. It's unfair. Having to do this under the impression of duty. /Canon Era. Merthur. Oneshot.


**.**

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Merlin nearly inhales his own saliva at the sheer, choking might of his horrified breath.

"You have to do what… to _what_?" he asks, bare-elbow deep in the washing tub of Arthur's laundry.

Sefa pauses from duming her own pile into another tub, cheeks burning. She twists her fingers together, nervously, voice small.

"In order to demonstrate my allegiance to the King, I must—"

"—I've never heard of anyone having to do _that_ ," Merlin interrupts, eyebrows rising with slight criticism. "Sounds like a load of rubbish to me. Who has been telling you this? If it's Gwaine, don't pay any mind to him. He's rarely being serious, especially if he's been on the mead…"

She's so young. Hardly been at the castle for two weeks, mousy-faced and quietly stammering out her words half the time. Sefa had already been subject to a hard time from the other servants. Not that Merlin couldn't relate.

(That was a different story entirely. Involved a live chicken and nearly getting his head lopped off by one of Uther's knights with an axe.)

But _this_?

Allowing her to believe she needed to display herself like an object to Arthur and then be _humiliated_ …?

Sefa's lips curve up. "Forgive me, but I believe the King already trusts you with his life." At the thoughtful, cautious look peering over at her, she ducks her head, embarrassed. "I've heard a great deal from the Queen about how he seeks your counsel. I assume you must be important."

"Well, of course I am. These socks don't clean themselves," Merlin says, wiggling a pair of them dripping in mid-air and chuckling at her sun-bright, amused expression blooming. That's more like it.

Pretty girls smiling were, admittedly, a favorite circumstance of his.

But that still left…

Merlin tilts his head back, blinking out water droplets as he violently rinses out the wads of clothing. Tension bleeding out. "No, this is mad," Merlin says to her, frowning. "I'll go in your place."

"Oh, no—"

Stubbornness only matches stubbornness, but he adds an heartfelt, practiced grin to seal the deal. "Trust me, it won't be a hardship." Sefa purses her mouth, confusion evident in his nearly ambiguous words. Or maybe it's wishful thinking. He wasn't always good about subtlety.

Merlin snorts, draining the tub. "We can spare your dignity," he adds.

"And yours?"

"My _what_?" The teasing hint does not go disregarded. Sefa grins back to him, relief visibly slumping her entire body.

"… Thank you, Merlin."

 **.**

 **.**

Gwen's presence seems to soothe whatever anticipation they all carry.

She knots the lacings to Arthur's snowy white robe around his waist, murmuring pleasantly to her husband, but Merlin cannot decipher it from across the bedchambers. Or, rather he's not trying very hard.

The air inside carries the odor of sweet, light oil permeating and a occasional burst of fresh, night air from the open window. There's also something hovering like arousal, not particularly man or woman as he can pick out from memory, faintly wreathed and heady. Perhaps it was both.

Merlin gathers the used dinner platters flecked with reasonably-sized leftovers. Arthur's platter, likely. Gwen had the decency from a lifetime of humility to _finish_ a delicious meal when served.

His eyes spot an annoyingly large crack in the table-wood and flicks a bit of his magic at it, watching it seal together like new.

"It's best you go too, Merlin."

He jerks his head round, staring wide-eyed at both Arthur and Gwen who must have been engaging in a conversation with him. She looks at Merlin expectantly, smoothing her brown hands over her night-gown. Arthur merely rolls his eyes at the obvious flash of clueless nature.

Merlin clears his throat, recovering.

"I expect I'll stay," he says, conversationally, despite how his heart rabbits towards his esophagus. "There has been a change in previous engagements. The serving girl isn't coming tonight, sire. An alternative solution has been made."

He could have been mistaken but Arthur's face loosened from irritation. No, Merlin wasn't mistaken. He knew Arthur. Knew his pure heart and the kind of man he was destined to become. Arthur wouldn't have to sought to humiliate a young girl like that, for the sake of barbaric tradition.

"Is that right?" Arthur's shoulders lift, as he says calmly, "Well—"

"I'll be taking her place instead."

That apparently isn't what his king was expecting. Gwen's mouth releases a soft, surprised noise, and Arthur's eyebrows furrow. " _You_?" he asks, expression stern. And Merlin sort of wants to knock it clean off.

"Merlin—"

He tucks his arms behind himself, clasping. Heels lifting slightly and Merlin's head inclining up. His body going as taunt as a bow-string.

Submission. It's the clearest display he can offer.

It bring on a dark, hungry emotion that darts behind Arthur's blue eyes, but he says nothing, a hand curling to one of Gwen's wrists. Merlin gives him a brave, little half-smile, eyes crinkling.

"If honorable tradition dictates it… then I haven't exactly pledged my _commitment_ yet, have I?" he says, silently appreciative in the way Arthur's robed body invisibly hums in anticipation. A better form. Merlin feels his magic answer it, drumming and thrumming in an echo.

Gwen faces her husband, glancing down at their entwined, ringed hands and then at Arthur's purposeful, unabashed look.

"Am I to take it that you seek my approval in this?" she asks quietly after a long moment.

The weighed silence must have been the suitable answer, as her dark eyes soften up at him and her hand separates from Arthur's. Gwen places her fingers under Arthur's chin, stroking there and holding it in place.

"… Of course you have it, Arthur."

"Thank you, Guinevere," Arthur murmurs, too low for anyone else to catch, mourning the loss of familiar, comforting heat as she steps away, her decorative, silken gown hem trailing the stone-floor after her.

Gwen reaches out, as she passes a bowing Merlin. "Treat him well, Merlin," the queen tells him, leaving a tiny squeeze to Merlin's arm.

"Always," he replied mischievously, as they share a furtive, benevolent look. Gwen laughs and kisses Merlin's cheek gently, eyes lovingly on Arthur. She disappears, still laughing, into the nearby antechamber.

Merlin arches an eyebrow. "Wasn't she supposed to be a witness?" he asks, curiously, bending down to pull off his wool-lined boots.

"For god's sake, _Mer_ lin," Arthur snaps on the luxuriously adorned bed Merlin only dreamed was the surface of _paradise_ , leaning back on the arrangement of fluffed pillows. "Stop prattling and come _here_. We don't have all night to waste on your ridiculousness."

Merlin politely nods, shedding his tattered, brown jacket, and with lips quirking. "That's disappointing," he says, halting at the bed's edge, a rasp in his breath. Arthur's eyes glare, hot and brilliant. But not towards anger. "Thought you'd enjoy taking your time."

"That would be hardly truth, seeing as you rarely _think_."

But Arthur's large, muscular hands grab onto him, helping Merlin settle over his lap. Pinpricks of feeling, tiny and pleasant, chase up Merlin's arms as those same hands grip lightly to Merlin's thighs.

"Don't be nervous, sire," Merlin pretends to chide him, ignoring the flash-flaring of heat churning in his own gut.

He grins unmistakably at the scowl and a mutter of treasonous behavior.

Merlin's hands shove off the robe at Arthur's chest, revealing far more scarred, golden skin and a triangular dusting of blond hair. He wonders mildly if that skin tastes as it appears — apple-smooth, buttery warmth.

A thumb runs softly over Arthur's collarbone, tracing and circling its shape before Merlin lets it drift, along with his forefinger and middle.

It's unfair. Having to do this under the impression of _duty_.

When he scrapes the edge of a blunt nail around Arthur's nipple, a sharp noise like a hiss of breath fills the otherwise hush bedchamber. Merlin resist the wild, primal urge to thrust down against Arthur's prick hardening slowly underneath him, his legs and knees on the mattress clenching in effort to keep himself situated above Arthur's lap.

In the time he had known him, Arthur was a complete prat, and insufferable on good days, but that didn't stop Merlin from imagining how _extraordinary_ it would be — rutting together, fingers slick, their hands pinned back, bucking and writhing, red, teeth-abused flesh, that prick hollowing him out, grunting, pleading soft and high cries.

But what good was imagining when they want _too_ much…

Arthur's expression falls from castle-stone to human vulnerability, as he examines Merlin. His hands press to Merlin a bit more forcefully.

"My life is yours," Merlin whispers hoarsely, with every inch of devotion, meeting summer-blue eyes. "This I swear to you." He swallows, exhaling and dragging his nose and parting mouth to Arthur's chest.

When his lips close around a nipple, he feels Arthur's hand cradling the nape of his neck, digging under the frayed material of his red, gem-bright neckerchief, toying with the strands of curled, black hair.

Slippery-wet, Merlin's tongue drags its rosy, little mound, groaning aloud when Arthur's hips intentionally drive up into him, jostling him. _Unfair_ , deeply so. Merlin answers it with less restraint, letting his full weight sink down on Arthur's lap and willingly riding another erratic, rough thrust, his own prick awakening with interest.

He sucks the nipple around his lips, at first shyly, unsure of the amount of pressure, and then Merlin tries pinching his teeth slightly, and gives it a long, fierce suck. Arthur's fingers then claw into Merlin's hair, yanking him forward. Merlin's heart jumps, as does his prick, at the filthy, _beautiful_ sound coming from Arthur.

There's fire in Merlin's blood, jetting and building drastic temperature through him. He grabs at Arthur's hips, steadying him and pushing apart the white robe. The king remains in his small-clothes, and it doesn't matter a damn second. Merlin's lips switch to the other nipple, tonguing and suckling until Arthur's skin feels as if it's burning-hot.

"That's enough," Arthur manages to get out, appearing flushed and his blond hair disheveled. He strokes his knuckles down Merlin's neck.

Merlin shakes his head, eyes lowered, mouth tingling.

"It's not," he retorts, softly, and accepts the kindness of Arthur's forehead to his.

"No, it's not," comes out in agreement, Arthur's breath trembling out. Barely there. "You have already proven your loyalty to me before this. I would never doubt you and I would never ask this of you, Merlin."

By the gods, he's fallen in love with an _idiot_.

"You wouldn't have to," Merlin says, tonelessly. He huffs out a frustrated sigh into Arthur's bare shoulder. "And now I've gone soft, dollophead."

A heavy rocking motion underneath him times itself perfectly with Arthur's teeth grinding at his sensitive earlobe, robbing the air from Merlin's lungs. It sparks little, white dots out of the corners of his vision.

"Until the candle goes out…"

Merlin pulls away, staring. Arthur's eyes are not on him. He searches, before noticing the desk. A single, yellowed candle melting away the hours. "Until then…" Arthur explains coolly, with large, Arthur-sized fingers roaming towards the thick laces of Merlin's breeches. "You are to remain here."

Like a tempest, the realization carries up in his chest. "Arthur—" Merlin whispers, pressing his mouth eagerly against Arthur's lips opening, pressing inside and moaning as Arthur's hands slide welcomed to his naked, body-warm skin.

"Gods, _yes_."

 **.**

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* * *

 _BBC Merlin isn't mine. I KNOW I HAVEN'T FINISHED UP "THE CATALYST" BUT I'VE GOT A BIRTHDAY TO CELEBRATE. HAPPY BIRTHDAY TO **EMILY** (GLOVE23 ON FFN AND AO3) AND I LOVE YOU LOTS, YOU LITTLE SHIT! I know how much you still love Merthur and decided to give you this. I hope you all love this too! Comments/thoughts are deeply appreciated! This came from the Kink Me, Merlin! #35 as a prompt asking for " **Arthur/Merlin**. __**Sucking the King's nipple or sughaim sine**." which was a practice done to show ''''loyalty and devotion'''' to their sovereign and it makes me giggly._


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